These new rulings [PDF], like the earlier one, are preliminary, but the U.S. Department of Commerce said it will nonetheless instruct customs officials to begin collecting duties on towers pending a final verdict in the case before the end of this year.

The rulings came in response to a trade complaint [PDF] filed by U.S. manufacturers –Trinity Structural Towers, DMI Industries, Katana Summit and Broadwind Energy, all based in the Midwest.

The fight over wind is just one aspect of a growing trade fissure on green energy between China and the West. Last week, a coalition of European companies asked the European Commission to investigate Chinese companies for allegedly dumping solar products in Europe, a complain that followed directly on the heels of similar – and so far successful – allegations in the United States.

While the solar market is measured in the billions of dollars, Commerce Department said imports of utility-scale wind towers from China in 2011 were valued at $222 million, and those from Vietnam at $79 million.

Still, the issue is volatile. Imported wind towers recently entered into the political debate about the U.S.’s clean-energy loan guarantee program when Rep. Mike Kelly (R-Pa.) complained that the 854-megawatt Caithness Shepherds Flat Wind Farm in Oregon, recipient of a $1.3 billion loan guarantee, used Chinese-manufactured towers in building what will soon open as one of the world’s largest wind farms.